1. Field
Embodiments relate to a salinity measuring apparatus to measure salinity of a solution.
2. Description of the Related Art
Kimchi is a traditional Korean food produced through fermentation. The rate of fermentation of Kimchi varies according to temperature and salinity.
The rate of fermentation of Kimchi is increased if temperature is high and salinity is low and is decreased if temperature is low and salinity is high.
Accordingly, in order to determine an appropriate Kimchi fermentation period, the internal temperature of a Kimchi storage chamber and salinity of Kimchi need to be measured.
The existing salinity measuring apparatus includes a salinity sensing unit having a pair of measuring electrodes and a capacitor, and a switching unit operating according to an output signal of the salinity sensing unit so as to switch a voltage supplied to the salinity sensing unit. Such a salinity measuring apparatus converts the voltage of the capacitor changed according to salinity into a frequency using predetermined upper and lower limit values and measures salinity according to the frequency.
However, in the existing salinity measuring apparatus, since the frequency is changed whenever salinity is measured, a measurement error may occur due to an internal impedance variation of the capacitor. Thus, it is difficult to accurately measure the salinity of food.
In addition, in the existing salinity measuring apparatus, when salinity is consecutively measured, a DC voltage component is partially supplied to the measuring electrodes, such that, over time, ions are accumulated in the measuring electrodes. Thus, electrical conductivity is lowered with over time. Accordingly, even when food having the same salinity is measured, since electrical conductivity is lowered due to ions accumulated in the measuring electrodes, the measured salinity may be changed whenever the salinity is measured. In addition, salinity lower than actual salinity may be measured and thus reliability of measured data may be reduced.
In addition, in the existing salinity measuring apparatus, since an oscillation frequency is increased as the salinity of the food is increased, switching loss of a self-oscillating circuit is generated.